:root{
  --paper:#f4f6f8;
  --surface:#ffffff;
  --surface-2:#eef1f5;
  --ink:#1a2233;
  --ink-2:#414a5c;
  --muted:#6c7686;
  --line:#e3e8ef;
  --line-2:#cfd7e2;
  --brand:#4154e8;
  --brand-strong:#3140cf;
  --brand-soft:#e9edff;
  --agent:#4f46e5;
  --agent-strong:#4338ca;
  --agent-soft:#eceffe;
  --fde:#0f8f80;
  --fde-strong:#0b7669;
  --fde-soft:#e1f4f0;
  --warm:#a16207;
  --font-sans:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei","Noto Sans SC",sans-serif;
  --font-serif:Georgia,"Times New Roman","Songti SC","SimSun",serif;
  --shadow-s:0 1px 2px rgba(26,34,51,.05),0 6px 16px rgba(26,34,51,.05);
  --shadow-m:0 2px 4px rgba(26,34,51,.06),0 18px 36px rgba(26,34,51,.09);
  --radius:14px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{margin:0;background:var(--paper);color:var(--ink);font-family:var(--font-sans);line-height:1.75;font-size:16px;-webkit-font-smoothing:antialiased}
a{color:inherit;text-decoration:none}
.wrap{max-width:1100px;margin:auto;padding:0 24px}
img{max-width:100%}

/* top bar */
.topbar{position:sticky;top:0;z-index:50;display:flex;align-items:center;justify-content:space-between;gap:24px;padding:14px 24px;background:rgba(244,246,248,.82);backdrop-filter:blur(10px);-webkit-backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
.topbar .inner{max-width:1100px;margin:auto;width:100%;display:flex;align-items:center;justify-content:space-between;gap:24px}
.brand{display:flex;align-items:center;gap:11px;font-weight:750;font-size:16px;letter-spacing:.01em;color:var(--ink)}
.mark{width:32px;height:32px;border-radius:9px;background:linear-gradient(135deg,#4154e8,#7c6cff);display:grid;place-items:center;color:#fff;font-size:11px;font-weight:800;box-shadow:0 4px 10px rgba(65,84,232,.32)}
.nav{display:flex;gap:26px;font-size:14px;color:var(--muted)}
.nav a{position:relative;padding:4px 0;transition:color .15s}
.nav a:hover{color:var(--brand)}
.nav a.active{color:var(--brand);font-weight:650}
.nav a.active::after{content:"";position:absolute;left:0;right:0;bottom:-2px;height:2px;border-radius:2px;background:var(--brand)}
.nav .cta{color:#fff!important;background:var(--brand);padding:8px 16px!important;border-radius:999px;font-weight:650;box-shadow:0 4px 12px rgba(65,84,232,.28)}
.nav .cta:hover{background:var(--brand-strong);color:#fff}

/* eyebrow / labels */
.eyebrow,.kicker{display:inline-flex;align-items:center;gap:8px;font-family:var(--font-serif);color:var(--brand);font-size:13px;font-weight:700;letter-spacing:.05em}
.eyebrow::before,.kicker::before{content:"";width:20px;height:1px;background:var(--brand)}

/* homepage hero */
.hero{position:relative;padding:64px 0 74px;overflow:hidden}
.hero-grid{max-width:1100px;margin:auto;padding:0 24px;display:grid;grid-template-columns:1.15fr .85fr;gap:56px;align-items:center}
.hero h1{font-size:clamp(38px,5.2vw,60px);line-height:1.1;letter-spacing:-.035em;margin:20px 0 20px;font-weight:800}
.hero h1 .hl{background:linear-gradient(100deg,var(--brand) 10%,#7c6cff 60%,#0f8f80);-webkit-background-clip:text;background-clip:text;color:transparent}
.hero .sub{max-width:600px;color:var(--ink-2);font-size:17px;margin:0;line-height:1.85}
.hero .actions{display:flex;gap:12px;flex-wrap:wrap;margin-top:30px}
.btn{display:inline-flex;align-items:center;gap:9px;padding:13px 22px;border-radius:999px;font-weight:700;font-size:15px;transition:.18s}
.btn.primary{background:var(--brand);color:#fff;box-shadow:0 6px 16px rgba(65,84,232,.3)}
.btn.primary:hover{background:var(--brand-strong);transform:translateY(-1px)}
.btn.ghost{background:var(--surface);color:var(--ink);border:1px solid var(--line-2)}
.btn.ghost:hover{border-color:var(--brand);color:var(--brand)}
.hero-art{position:relative}
.hero-art .bg-grid{position:absolute;inset:-40px;z-index:0;opacity:.5;background-image:linear-gradient(var(--line) 1px,transparent 1px),linear-gradient(90deg,var(--line) 1px,transparent 1px);background-size:34px 34px;-webkit-mask-image:radial-gradient(circle at 50% 50%,#000 30%,transparent 72%);mask-image:radial-gradient(circle at 50% 50%,#000 30%,transparent 72%)}
.shelf{position:relative;z-index:1;display:flex;gap:22px;justify-content:center;align-items:flex-end;padding:26px}
.shelf .shelf-note{position:absolute;top:-6px;right:6px;font-family:var(--font-serif);font-size:12px;color:var(--muted);letter-spacing:.08em}

/* book cover mockup */
.cover{position:relative;width:158px;border-radius:6px;overflow:hidden;color:#fff;display:flex;flex-direction:column;justify-content:space-between;padding:15px 15px 14px;box-shadow:var(--shadow-m)}
.cover::before{content:"";position:absolute;left:0;top:0;bottom:0;width:9px;background:rgba(0,0,0,.16)}
.cover .top{font-family:var(--font-serif);font-size:9px;letter-spacing:.16em;opacity:.85;font-weight:700}
.cover .title{font-size:16px;line-height:1.32;font-weight:750;margin:18px 0 0;letter-spacing:.01em}
.cover .title small{display:block;font-size:11px;font-weight:600;opacity:.85;margin-top:8px}
.cover .bottom{font-size:8.5px;opacity:.72;letter-spacing:.08em}
.cover.agent{background:linear-gradient(155deg,#2f2b7a 0%,#4338ca 52%,#7c6cff 100%)}
.cover.fde{background:linear-gradient(155deg,#0a4b43 0%,#0b7669 52%,#23b5a2 100%)}
.cover.tall{height:228px}
.cover.small{width:132px;height:190px}
.cover.small .title{font-size:14px}

/* sections */
.section{padding:60px 0 84px}
.section.alt{background:var(--surface-2)}
.section-head{max-width:680px;margin-bottom:38px}
.section-head h2{font-size:clamp(26px,3.4vw,38px);line-height:1.22;letter-spacing:-.03em;margin:14px 0 0;font-weight:800}
.section-head p{color:var(--muted);font-size:16px;margin:14px 0 0;line-height:1.8}

/* book cards (home) */
.books{display:grid;grid-template-columns:1fr 1fr;gap:22px}
.book-card{position:relative;display:flex;flex-direction:column;justify-content:space-between;background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:26px;min-height:250px;box-shadow:var(--shadow-s);transition:.2s;overflow:hidden}
.book-card::after{content:"";position:absolute;right:-40px;top:-40px;width:150px;height:150px;border-radius:50%;background:var(--accent-soft,var(--brand-soft));opacity:.5}
.book-card:hover{transform:translateY(-4px);box-shadow:var(--shadow-m);border-color:var(--line-2)}
.book-card.agent{--accent:var(--agent);--accent-soft:var(--agent-soft)}
.book-card.fde{--accent:var(--fde);--accent-soft:var(--fde-soft)}
.book-card .book-top{display:flex;gap:20px;align-items:flex-start}
.book-card .meta .vol{font-family:var(--font-serif);font-size:12px;color:var(--accent);letter-spacing:.14em;font-weight:700}
.book-card .meta h3{font-size:21px;line-height:1.4;margin:10px 0 8px;font-weight:800;letter-spacing:-.01em}
.book-card .meta p{color:var(--muted);font-size:14.5px;margin:0;line-height:1.8}
.book-card .go{display:inline-flex;align-items:center;gap:8px;margin-top:22px;color:var(--accent);font-weight:700;font-size:14.5px}
.book-card .go .arrow{transition:transform .18s}
.book-card:hover .go .arrow{transform:translateX(4px)}

/* scenarios (reading path) */
.paths{display:grid;grid-template-columns:1fr 1fr;gap:22px}
.scenario{display:flex;align-items:center;gap:18px;background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:24px;box-shadow:var(--shadow-s);transition:.18s}
.scenario:hover{border-color:var(--brand);transform:translateY(-3px);box-shadow:var(--shadow-m)}
.scenario .tag{width:46px;height:46px;flex:none;border-radius:12px;display:grid;place-items:center;font-family:var(--font-serif);font-weight:700;font-size:17px;background:var(--brand-soft);color:var(--brand)}
.scenario.agent .tag{background:var(--agent-soft);color:var(--agent)}
.scenario.fde .tag{background:var(--fde-soft);color:var(--fde)}
.scenario strong{font-size:16.5px;font-weight:750;display:block}
.scenario small{color:var(--muted);font-size:13px;display:block;margin-top:4px}

/* about */
.about{background:linear-gradient(135deg,#1a2233,#26334d);color:#eef1f5;border-radius:20px;padding:44px 46px;box-shadow:var(--shadow-m)}
.about .kicker{color:#9aa7ff}
.about .kicker::before{background:#9aa7ff}
.about h2{font-size:clamp(24px,3vw,32px);margin:16px 0 0;font-weight:800;letter-spacing:-.02em;color:#fff}
.about p{color:#c6cedc;font-size:16px;line-height:1.9;margin:18px 0 0;max-width:720px}
.about .about-note{border-left:3px solid #7c6cff;padding-left:18px;margin-top:24px;color:#dfe5f1}

/* footer */
.footer{border-top:1px solid var(--line);padding:30px 0 44px;display:flex;justify-content:space-between;flex-wrap:wrap;gap:24px;color:var(--muted);font-size:13px;max-width:1100px;margin:auto;padding-left:24px;padding-right:24px}
.footer small{display:block;line-height:1.9;margin-top:6px}
.footer a{color:var(--brand)}
.footer .icp-registration{width:100%;display:flex;justify-content:center;border-top:1px solid var(--line);padding-top:20px;margin-top:2px}
.footer .icp-registration a{display:inline-flex;align-items:center;gap:8px;color:var(--muted);font-size:12px;line-height:1.5;text-decoration:none}
.footer .icp-registration a:hover{color:var(--brand)}
.footer .icp-mark{display:inline-grid;place-items:center;width:24px;height:24px;border:1px solid var(--line-2);border-radius:5px;background:var(--surface);color:var(--brand);font-size:9px;font-weight:700;letter-spacing:-.04em}
.footer .to-top{flex:none}
.footer .to-top a{display:inline-flex;align-items:center;gap:6px;border:1px solid var(--line-2);border-radius:999px;padding:8px 14px;color:var(--ink);font-size:13px;transition:.15s}
.footer .to-top a:hover{border-color:var(--brand);color:var(--brand)}

/* crumbs */
.crumbs{font-size:13px;color:var(--muted);padding:26px 0 0;max-width:1100px;margin:auto;padding-left:24px;padding-right:24px}
.crumbs a{color:var(--brand)}

/* book index page */
.book-hero{max-width:1100px;margin:auto;padding:44px 24px 30px;display:grid;grid-template-columns:170px 1fr;gap:38px;align-items:center}
.book-hero h1{font-size:clamp(28px,4vw,44px);line-height:1.16;letter-spacing:-.03em;margin:14px 0 14px;font-weight:800}
.book-hero .sub{color:var(--ink-2);font-size:16.5px;max-width:660px;margin:0;line-height:1.85}
.book-stats{display:flex;gap:9px;flex-wrap:wrap;margin-top:22px}
.stat{background:var(--surface);border:1px solid var(--line);border-radius:999px;padding:6px 13px;font-size:12.5px;font-weight:650;color:var(--ink-2)}
.chapters{max-width:1100px;margin:auto;padding:6px 24px 70px}
.chapters h2{font-size:26px;margin:0 0 26px;font-weight:800;letter-spacing:-.02em}
.chapter-list{display:grid;grid-template-columns:1fr 1fr;gap:13px}
.chapter{display:flex;gap:14px;align-items:flex-start;background:var(--surface);border:1px solid var(--line);border-radius:11px;padding:16px 17px;box-shadow:var(--shadow-s);transition:.16s}
.chapter:hover{transform:translateY(-2px);border-color:var(--line-2);box-shadow:var(--shadow-m)}
.chapter .num{font-size:12px;font-weight:750;color:var(--brand);min-width:46px;font-family:var(--font-serif);padding-top:2px}
.chapter strong{font-size:15px;line-height:1.45;font-weight:700}
.chapter small{display:block;color:var(--muted);font-size:11.5px;margin-top:5px}
.note{background:var(--surface-2);border:1px solid var(--line);border-radius:12px;padding:22px 24px;color:var(--ink-2);margin-top:26px;font-size:14.5px;line-height:1.8}
.note strong{display:block;color:var(--ink);margin-bottom:6px;font-weight:750}

/* reading layout */
.layout{max-width:1100px;margin:auto;padding:34px 24px 80px;display:grid;grid-template-columns:228px minmax(0,1fr);gap:52px;align-items:start}
.toc{position:sticky;top:92px;max-height:calc(100vh - 110px);overflow:auto;padding-right:6px}
.toc-title{font-size:11.5px;font-weight:750;letter-spacing:.12em;color:var(--muted);margin-bottom:12px;text-transform:uppercase}
.toc a{display:block;border-left:2px solid var(--line);padding:7px 12px;color:var(--muted);font-size:13px;line-height:1.45;transition:.14s}
.toc a:hover{color:var(--brand)}
.toc a.active{border-color:var(--brand);color:var(--brand);background:var(--brand-soft)}

/* reading hero */
.page-head{max-width:1100px;margin:auto;padding:34px 24px 6px}
.page-head .eyebrow{font-family:var(--font-serif)}
.page-head h1{font-size:clamp(28px,4vw,44px);line-height:1.16;letter-spacing:-.03em;margin:16px 0 14px;font-weight:800}
.page-head p{color:var(--ink-2);font-size:16px;max-width:680px;margin:0;line-height:1.85}
.status-pill{display:inline-flex;align-items:center;gap:7px;border-radius:999px;background:var(--brand-soft);color:var(--brand);font-size:12px;font-weight:700;padding:5px 12px;margin:0 0 4px}
.status-pill.intro{background:var(--surface);border:1px solid var(--line-2);color:var(--muted)}

/* prose */
.prose{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:44px 52px 40px;box-shadow:var(--shadow-s)}
.prose h2{font-size:28px;line-height:1.35;letter-spacing:-.02em;margin:0 0 20px;padding-top:10px;font-weight:800}
.prose h2::after{content:"";display:block;width:44px;height:3px;border-radius:3px;background:var(--brand);margin-top:14px}
.prose h3{font-size:21px;line-height:1.45;margin:40px 0 12px;color:var(--ink);font-weight:750}
.prose h4{font-size:17px;margin:26px 0 8px;font-weight:700}
.prose p{font-size:16px;line-height:1.95;margin:0 0 20px;color:#2b3346}
.prose p.caption{font-size:13px;color:var(--muted);text-align:center;margin-top:-10px}
.prose figure{margin:22px 0;text-align:center}
.prose figure img{display:block;width:auto;max-width:100%;height:auto;margin:auto;border-radius:6px}
.prose p.toc-lead{color:var(--muted)}
.prose p.toc-line{font-size:14px;line-height:1.7;border-bottom:1px dashed var(--line);padding:6px 0;margin:0;color:#3a4356}
.prose .table-wrap{overflow:auto;margin:26px 0;border:1px solid var(--line);border-radius:10px}
.prose table{border-collapse:collapse;width:100%;font-size:14px}
.prose th,.prose td{border:1px solid var(--line);padding:11px 14px;text-align:left;vertical-align:top}
.prose th{background:var(--surface-2);color:var(--ink);font-weight:700}
.prose tr:nth-child(even) td{background:#fafbfc}
.related{display:grid;grid-template-columns:1fr 1fr;gap:13px;margin-top:38px;padding-top:26px;border-top:1px solid var(--line)}
.related a{border:1px solid var(--line);border-radius:11px;background:var(--surface);padding:16px;color:var(--ink);transition:.16s}
.related a:hover{border-color:var(--brand);box-shadow:var(--shadow-s)}
.related a.next{text-align:right}
.related small{display:block;color:var(--muted);font-size:11.5px}
.related strong{display:block;margin-top:5px;font-size:14.5px;color:var(--brand);line-height:1.5}
.related a:first-child:last-child{grid-column:1/-1;text-align:center}

@media(max-width:860px){
  .hero-grid{grid-template-columns:1fr;gap:40px;padding-top:16px}
  .hero-art .shelf{justify-content:center}
  .books,.paths{grid-template-columns:1fr}
  .layout{grid-template-columns:1fr;gap:22px}
  .toc{position:static;display:flex;overflow-x:auto;gap:7px;padding-bottom:6px;max-height:none}
  .toc-title{display:none}
  .toc a{white-space:nowrap;border:1px solid var(--line);border-radius:999px;padding:7px 12px;font-size:12.5px}
  .toc a.active{border-color:var(--brand)}
  .book-hero{grid-template-columns:128px 1fr;gap:24px}
  .chapter-list{grid-template-columns:1fr}
  .prose{padding:34px 30px 32px}
  .footer{display:block}
  .footer .to-top{margin-top:14px}
}
@media(max-width:560px){
  .wrap,.hero-grid,.crumbs,.footer,.book-hero,.chapters,.layout,.page-head{padding-left:18px;padding-right:18px}
  .topbar .inner{padding:0 4px}
  .nav{display:none}
  .hero h1{font-size:34px}
  .book-hero{grid-template-columns:1fr}
  .cover.tall{width:150px;height:210px}
  .cover.small{display:none}
  .prose{padding:28px 22px 26px;border-radius:12px}
  .related{grid-template-columns:1fr}
  .about{padding:32px 26px}
}